Facebook is taking action, that appears to be retaliatory, against researchers that are investigating it.

Researchers from New York University have been investigating how political advertising money is spent on the social media platform and shed a light on disinformation. The researchers created a browser plug-in that allowed users to capture ads they saw and post the data to a public database.

Facebook has since blocked the researchers, claiming they are breaking the company’s Terms of Service by scraping data, saying so in a blog post:

Today, we disabled the accounts, apps, Pages and platform access associated with NYU’s Ad Observatory Project and its operators after our repeated attempts to bring their research into compliance with our Terms. NYU’s Ad Observatory project studied political ads using unauthorized means to access and collect data from Facebook, in violation of our Terms of Service. We took these actions to stop unauthorized scraping and protect people’s privacy in line with our privacy program under the FTC Order. 

There’s only one problem with Facebook’s stance: The data NYU’s browser plug-in captures is not from private individuals, but from ad companies whose ads are already publicly available — they wouldn’t be very effective ads if they weren’t.

Facebook’s actions are already drawing criticism, with its actions being seen as a poorly veiled attempt to silence its critics. The result has been calls for increased scrutiny, including from no less that Senator Ron Wyden, well-known for his staunch pro-privacy stance.